This TSB on the subject
An improperly functioning input speed sensor or output speed sensor on a 1999-2001 Sonata, 2001 Elantra, 2001 Santa Fe and 2001 XG300 may result in the following conditions:
Harsh P-R or P-D engagement shock
Transaxle allows acceleration in 1st gear to 5000 rpm, then shifts into 3rd gear fail-safe
Check Engine light on
Diagnostic trouble codes:
P0715 (no input speed sensor signal - open/short)
P0720 (no output speed sensor signal - open/short)
P1529 (TCM MIL request to ECM)
Check for DTCs in both the Engine and Automatic Transaxle menus. If you find:
DTC REPAIR PROCEDURE REFERENCE
P0715Replace input speed sensor
P0720Replace output speed sensor
Fig. 1: Identifying Input And Output Speed Sensors
Courtesy of HYUNDAI MOTOR CO.
Drive the vehicle for at least two key-on to key-off driving cycles. If the codes do not reset, return the vehicle to the customer. If P0715 or P0720 return, go to step 2.
Use a DVOM to check the resistance of the wiring between the TCM and the input sensors and output sensors. If the resistance is:
More than 1 ohm, repair or replace the wiring harness
Less than 1 ohm, go to Step 3.
Replace the transaxle control module (TCM).
Monday, November 22nd, 2010 AT 2:33 AM